Gonorrheal MtrE Peptides and Vaccines

ABSTRACT

The invention is directed to MtrE peptides and their use in gonorrhea vaccines.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with government support under A1031496 awardedby National Institutes of Health (NIH). The government has certainrights in the invention.

SEQUENCE LISTING SUBMISSION VIA EFS-WEB

A computer readable text file, entitled “SequenceListing.txt” created onor about Jun. 4, 2018 with a file size of about 16 kb contains thesequence listing for this application and is hereby incorporated byreference in its entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The invention is directed to MtrE peptides, including chimeric peptidescomprising the MtrE peptides, and their use in gonorrhea vaccines.

Background of the Invention

Gonorrhea is the second most frequently reported infection to the Centerfor Disease Control (CDC) and, as such, accrues significant publichealth costs. Similarly, gonorrhea is the second most commonly reportedinfection in the U.S. military. Gonorrhea, like all sexually transmittedinfections (STIs), disproportionately occurs in adolescents and youngadults; therefore diagnosis and treatment of gonorrhea significantlytaxes the public health care system. Serious morbidity arises, primarilyin women, due to ascension of gonococcal infection to the endometriumand fallopian tubes, which leads to pelvic inflammatory disease (PID).PID and the post-infection complications, chronic pelvic pain,infertility and ectopic pregnancy, also occur at high incidence in theU.S. and worldwide. Ectopic pregnancy is a life-threatening conditionand the fourth leading cause of maternal death in the U.S. Another causefor concern is the demonstration that gonococcal infection is associatedwith a risk for increased transmission of the human immunodeficiencyvirus (HIV).

Current prevention strategies for gonorrhea are limited to safe-sexcounseling and the identification and treatment of infected individuals.Alarmingly, antibiotic resistance emerges rapidly in Neisseriagonorrhoeae, which threatens the current control measures. Only oneclass of antibiotics, the extended spectrum cephalosporins (ESCs), isleft to treat gonococcal infections and therefore, this pathogenrecently reached “super bug” status in 2007 (CDC, 2007). Since then,decreased susceptibility to ESCs has been reported, and in 2009 anESC-resistant N. gonorrhoeae strain was isolated in Japan (CDC, 2011;Unemo, et al, 2010). The inability to treat gonorrhea may soon become areality. Therefore, there is an urgent need for a gonorrhea vaccine.

The gonococcal MtrC-MtrD-MtrE (MtrCDE) active efflux pump is criticalfor experimental genital tract infection of female mice. Mutants in thispump are the most attenuated of all the mutants we have tested in thismodel. MtrC and MtrD are periplasmic and inner membrane proteins,respectively. The MtrE subunit, in contrast, is located in the bacterialouter membrane. Based on homology to other RND pumps and in silicoanalysis of the predicted secondary structure of the MtrE protein, it islikely that MtrE has two surface-exposed loops that could possibly betargeted for a vaccine.

SUMMARY OF THE INVENTION

The present application is directed to isolated MtrE peptides comprisingan amino acid sequence that is at least 80% identical to residues 23-467of SEQ ID NO:1, or an amino acid sequence that is at least 80% identicalto residues 23-155 of SEQ ID NO:1 or an amino acid sequence that is atleast 80% identical to residues 313-467 of SEQ ID NO:1.

The present invention is also directed to methods of producing isolatedMtrE proteins, with the method comprising culturing a host cellharboring a vector coding for the MtrE protein in culture conditions inwhich expression of the MtrE protein from the vector occurs in the host,and purifying the MtrE protein from the cell culture.

The present invention also directed to pharmaceutical compositioncomprising the isolated MtrE proteins of the present invention andmethods of immunizing a subject against Neisseria gonorrhoeae (N.gonorrhoeae) comprising administering the pharmaceutical compositions ofthe present invention in an immunogenically effective amount.

The present invention also relates to an antibody or antibody fragmentthat binds a MtrE protein in Neisseria gonorrhoeae (N. gonorrhoeae).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts the binding of MtrE₂₁₋₄₆₇ specific antiserum to thesurface of N. gonorrhoeae.

FIG. 2 depicts the bactericidal activity of MtrE₂₁₋₄₆₇ specificantiserum against three different gonococcal strains but not anMtrCDE-deficient mutant.

FIG. 3 depicts the specificity of antisera against MtrE peptides 112-118(predicted loop 1) and 313-332 (predicted loop 2) of the MtrE protein asassessed by Western blot.

FIG. 4 depicts the capacity of affinity-purified antibodies against thepredicted loop 2 peptide (MtrE 311-332) to inhibit pump function in wildtype FA19 bacteria and strain JF-1, an over-producer of the MtrCDEactive efflux pump. Antibodies to an unrelated antigen, Opa_(SV), is notinhibitory at the same dilutions.

FIG. 5 depicts a construct of the present invention. The left panel (A)shows the resulting protein MtrE Loop 1 sequence from the MtrE-PorinLoop 8 fusion construct. On the right (B) uninduced and induced E. colicultures were subjected to SDS-PAGE and stained with coomassie blue toshow protein expression. A 50 kD protein is seen in the induced culturesand is indicative of the MtrE-Porin fusion protein. This band is absentin the uninduced cultures

DETAILED DESCRIPTION OF THE INVENTION

The present application is directed to isolated MtrE peptides. As usedherein, the terms “protein” and “peptide” are used interchangeably andsimply used to denote at least a polymer, branched or unbranched, ofamino acid residues. As used herein, the term “isolated,” when used inconjunction with proteins and nucleic acids, is used to indicate thatthe proteins or nucleic acids are present in a form in which the proteindoes not naturally occur. For example, the MtrE protein in the presentapplication is a protein that naturally occurs the in outer membrane ofN. gonorrhoeae. Thus, an “isolated MtrE” protein is a protein that doesnot occur as part of the outer membrane of N. gonorrhoeae.

The isolated proteins of the present invention can occur in any in vitroor in vivo setting. For example, a cell containing a vector that encodesan MtrE protein of the present invention encompasses the term “isolatedprotein” as used herein. In another example, a bacterium other than N.gonorrhoeae expressing an MtrE protein in its outer membrane is alsoencompassed by the term “isolated protein” as used herein. Thus, an MtrEprotein present in a cell that does not normally express MtrE,regardless of how it was introduced into the cell, is also encompassedwithin the term “isolated protein” as used herein.

However, a nucleic acid contained in a clone that is a member of alibrary, e.g., a genomic or cDNA library, that has not been isolatedfrom other members of the library, e.g., in the form of a homogeneoussolution containing the clone and other members of the library, or achromosome isolated or removed from a cell or a cell lysate, e.g., a“chromosome spread,” as in a karyotype, is not “isolated” for thepurposes of the invention. As discussed further herein, isolated nucleicacid molecules according to the present invention may be producednaturally, recombinantly, or synthetically.

Of course, the isolated MtrE proteins or fragments described herein canbe purified or substantially purified. As used herein, the term“purified” when used in reference to a protein or nucleic acid, meansthat the concentration of the molecule being purified has been increasedrelative to other molecules associated with it in its naturalenvironment, or environment in which it was produced, found orsynthesized. One of skill in the art would recognize that these “othermolecules” might include proteins, nucleic acids, lipids and sugars butgenerally do not include water, solvents, buffers, and reagents added tomaintain the integrity or facilitate the purification of the moleculebeing purified. For example, even if a protein is diluted with anaqueous solvent during affinity chromatography, the proteins arepurified by this chromatography if other naturally associated moleculesdo not bind to the column and are separated from the subject proteins.According to this definition, a substance may be 5% or more, 10% ormore, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more,70% or more, 80% or more, 90% or more, 95% or more, 98% or more, 99% ormore, or 100% pure when considered relative to its contaminants.

The naturally occurring MtrE protein is part of the multipletransferable resistance efflux system (MtrCDE) present in Neisseriagonorrhoeae (N. gonorrhoeae). The term “N. gonorrhoeae” (or Neisseriagonorrhoeae) as used herein refers to any strain of the bacterium,including but not limited to the strains FA1090, FA19, MS11, and F62.The MtrE protein is the outer membrane protein portion of the effluxpump. The MtrE protein forms the outer membrane pore of the GcMtrC-MtrD-MtrE (multiple transferable resistance) and FarA-FarB-MtrE(fatty acid resistance) multidrug resistance (MDR) efflux systems. MtrEfunctions with the inner membrane transporter and a periplasmicaccessory protein to capture antimicrobial substrates and transport themthrough the periplasm to the external milieu. Clinical evidence suggeststhe MtrC-MtrD-MtrE active efflux pump system protects Gc from innatemucosal defenses. Natural substrates of the MtrC-MtrD-MtrE andFarA-FarB-MtrE systems found on urogenital or rectal mucosa includefatty acids, bile salts, antimicrobial peptides, and fecal lipids. Thefull length amino acid sequence of the N. gonorrhoeae MtrE, includingthe leader sequence, is presented herein as SEQ ID NO:1 below. The aminoacid sequence of SEQ ID NO:1 contain the leader sequence at residues1-20, such that the “mature MtrE protein” generally is amino acids21-467 of SEQ ID NO:1, below. MtrE peptides 112-118 and 313-332, whichcorrespond to surface-exposed loops 1 and 2, respectively and areindicated in the sequence below by single and double underlining,respectively.

(SEQ ID NO: 1) MNTTLKTTLT SVAAAFALSA CTMIPQYEQP KVEVAETFQNDTSVSSIRAV DLGWHDYFAD PRLQKLIDIA LERNTSLRTAVLNSEIYRKQ YMIERNNLLP TLAANANGSR QGSLSGGNVSSSYNVGLGAA SYELDLFGRV RSSSEAALQG YFASVANRDAAHLSLIATVA KAYFNERYAE EAMSLAQRVL KTREETYNAVRIAVQGRRDF RRRPAPAEAL IESAKADYAH AARSREQARNALATLINRPI PEDLPAGLPL DKQFFVEKLP AGLSSEVLLDRPDIRAAEHA LKQANANIGA ARAAFFPSIR LTGSVGTGSVELGGLFKSGT GVWAFAPSIT LPIFTWGTNK ANLDVAKLRQQAQIVAYESA VQSAFQDVAN ALAAREQLDK AYDALSKQSRASKEALRLVG LRYKHGVSGA LDLLDAERSS YSAEGAALSAQLTRAENLAD LYKALGGGLK RDTQTGK

The present invention is directed to the full length MtrE protein, themature MtrE protein, and fragments thereof. As used herein, the term“MtrE protein” (or “MtrE peptide”) is used to mean proteins comprisingthe amino acid sequence of the mature MtrE, as defined by the amino acidsequence herein, as well as the orthologs, fragments, fusions andvariants thereof that are disclosed herein. An MtrE protein as definedherein need not have the identical function of the wild-type MtrEprotein and need not have any function. In one embodiment of the presentinvention, the MtrE proteins of the present invention possess at leastpartial functionality as wild-type, mature MtrE proteins.

The term “fragment,” when used in connection with a protein, is used tomean a peptide that contains a sequence of contiguous amino acids takenfrom the full length or mature MtrE protein. In specific embodiments,the MtrE fragments of the present invention comprise alternativelyconsist of about 5 to 10, 10 to 15, 15 to 20, 20 to 25, 25 to 30, 30 to35, 35 to 40, 40 to 45, 45 to 50, 50 to 55, 55 to 60, 60 to 65, 65 to70, 70 to 75, 75 to 80, 80 to 85, 85 to 90, 90 to 95, 95 to 100, 100 to105, 105 to 110, 110 to 115, 115 to 120, 120 to 125, 125 to 130, 130 to135, 135 to 140, 140 to 145, 145 to 150, 150 to 155, 155 to 160, 160 to165, 165 to 170, 170 to 175, 175 to 180, 180 to 185, 185 to 190, 190 to195, 195 to 200, 200 to 205, 205 to 210, 210 to 215, 215 to 220, 220 to225, 225 to 230, 230 to 235, 235 to 240, 240 to 245, 245 to 250, 250 to255, 255 to 260, 260 to 265, 265 to 270, 270 to 275, 275 to 280, 280 to285, 285 to 290, 290 to 295, 295 to 300, 300 to 305, 305 to 310, 310 to315, 315 to 320, 320 to 325, 325 to 330, 330 to 335, 335 to 340, 340 to345, 345 to 350, 350 to 355, 355 to 360, 360 to 365, 365 to 370, 370 to375, 375 to 380, 380 to 385, 385 to 390, 390 to 395, 395 to 400, 400 to405, 405 to 410, 410 to 415, 415 to 420, 420 to 425, 425 to 430, 430 to435, 435 to 440, 440 to 445, 445 to 450, 450 to 455, 456, 457, 458, 459,460, 461, 462, 463, 464, 465 or 466 contiguous amino acids of SEQ IDNO:1.

In specific embodiments, the invention provides isolated MtrE proteinfragments with amino acid sequences comprising or alternativelyconsisting of amino acid residues 23-467 of SEQ ID NO:1, amino acidresidues 23-155 of SEQ ID NO:1 or an amino acid residues 313-467 of SEQID NO:1. In other specific embodiments, the invention provides isolatedMtrE peptides with amino acid sequences comprising or alternativelyconsisting of amino acid residues 112-118 of SEQ ID NO:1, and comprisingor alternatively consisting of amino acid residues 313-332 of SEQ IDNO:1.

The invention also provides for variants of the MtrE proteins orfragments as described herein. Variants include but are not limited tonaturally-occurring allelic variants, as well as mutants, variants orany other non-naturally occurring variants. In one embodiment, thevariants cross-react with antibodies against an MtrE peptide of thepresent invention.

Allelic variants are very common in nature. For example, N. gonorrhoeaecan be represented by a variety of strains or serovars that differ fromeach other by minor allelic variations. An allelic variant is analternate form of a polypeptide that is often characterized as having asubstitution, deletion, or addition of one or more amino acids that doesnot substantially alter the biological function of the polypeptide incells in which it naturally occurs. For example, a polypeptide thatfulfills the same biological function in different strains can have anamino acid sequence that may not be identical in each of the variousstrains of N. gonorrhoeae. Such an allelic variation may be equallyreflected at the nucleic acid molecule level.

Nucleic acid molecules, e.g., DNA molecules, encoding allelic variantscan easily be retrieved by the polymerase chain reaction (PCR)amplification of genomic bacterial DNA extracted by conventionalmethods. This involves the use of synthetic oligonucleotide primersmatching upstream and downstream sequences of the 5′ and 3′ ends of theencoding domains. Typically, a primer can consist of 10 to 40, and evenfrom 15 to 25 nucleotides, and it can often be advantageous to selectprimers containing G/C nucleotides in a proportion sufficient to ensureefficient hybridization.

In specific examples, the invention is directed to isolated variants ofMtrE proteins comprising, or in the alternative consisting of an aminoacid sequence that is at least 80% identical to residues 23-467 of SEQID NO:1, or an amino acid sequence that is at least 80% identical toresidues 23-155 of SEQ ID NO:1 or an amino acid sequence that is atleast 80% identical to residues 313-467 of SEQ ID NO:1. In additionalembodiments, the invention is directed to isolated MtrE proteins thathave amino acid sequences comprising, or in the alternative consistingof sequences, that are at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%,93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identical to residues 23-467of SEQ ID NO:1. In more embodiments, the invention is directed toisolated MtrE proteins that have amino acid sequences comprising, or inthe alternative consisting of sequences, that are at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% A and100% identical to residues 23-155 of SEQ ID NO:1. In still moreembodiments, the invention is directed to isolated MtrE proteins thathave amino acid sequences comprising, or in the alternative consistingof sequences, that are at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%,93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identical to residues 313-467of SEQ ID NO:1. In still more embodiments, the invention is directed toisolated MtrE proteins that have amino acid sequences comprising, or inthe alternative consisting of sequences, that are at least 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100%identical to residues 112-118 of SEQ ID NO:1. In still more embodiments,the invention is directed to isolated MtrE proteins that have amino acidsequences comprising, or in the alternative consisting of sequences,that are at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%,96%, 97%, 98%, 99% and 100% identical to residues 313-332 of SEQ IDNO:1.

The MtrE proteins of the present invention may also comprisesubstitution variants. Substitution variants include those polypeptideswherein one or more amino acid residues of the MtrE proteins are removedand replaced with alternative residues. In one embodiment, thesubstitution variants of the present invention are conservative innature. Conservative substitutions for this purpose may be defined asset out in the tables below, but in general are considered to be thosesubstitutions that do not affect the overall function orthree-dimensional structure of the protein. Amino acids can beclassified according to physical properties and contribution tosecondary and tertiary protein structure. A conservative substitution isrecognized in the art as a substitution of one amino acid for anotheramino acid that has similar properties. Exemplary conservativesubstitutions are set out in below.

TABLE I Conservative Substitutions Side Chain Characteristic Amino AcidAliphatic Non-polar Gly, Ala, Pro, Iso, Leu, Val Polar-uncharged Cys,Ser, Thr, Met, Asn, Gln Polar-charged Asp, Glu, Lys, Arg Aromatic His,Phe, Trp, Tyr Other Asn, Gln, Asp, Glu

Alternatively, conservative amino acids can be grouped as described inLehninger (1975) Biochemistry, Second Edition; Worth Publishers, pp.71-77, as set forth below.

TABLE II Conservative Substitutions Side Chain Characteristic Amino AcidNon-polar (hydrophobic) Aliphatic: Ala, Leu, Iso, Val, Pro Aromatic:Phe, Trp Sulfur-containing: Met Borderline: Gly Uncharged-polarHydroxyl: Ser, Thr, Tyr Amides: Asn, Gln Sulfhydryl: Cys Borderline: GlyPositively Charged (Basic): Lys, Arg, His Negatively Charged (Acidic)Asp, Glu

And still other alternative, exemplary conservative substitutions areset out below.

TABLE III Conservative Substitutions Original Residue ExemplarySubstitution Ala (A) Val, Leu, Ile Arg (R) Lys, Gln, Asn Asn (N) Gln,His, Lys, Arg Asp (D) Glu Cys (C) Ser Gln (Q) Asn Glu (E) Asp His (H)Asn, Gln, Lys, Arg Ile (I) Leu, Val, Met, Ala, Phe Leu (L) Ile, Val,Met, Ala, Phe Lys (K) Arg, Gln, Asn Met (M) Leu, Phe, Ile Phe (F) Leu,Val, Ile, Ala Pro (P) Gly Ser (S) Thr Thr (T) Ser Trp (W) Tyr Tyr (Y)Trp, Phe, Thr, Ser Val (V) Ile, Leu, Met, Phe, Ala

The variants of the MtrE proteins and fragments thereof also includepeptides comprising non-traditional amino acid residues. For example,the MtrE peptides and fragments thereof may include residues in the “Dconfiguration” or amino acids that do not normally occur in proteins,such as but not limited to citrulline, ornithine, hypusine,selenocysteine α-amino isobutyric acid, 4-aminobutyric acid, Abu,2-amino butyric acid, γ-Abu, ε-Ahx, 6-amino hexanoic acid, Aib, 2-aminoisobutyric acid, 3-amino propionic acid, norleucine, norvaline,hydroxyproline, sarcosine, cysteic acid, t-butylglycine, t-butylalanine,phenylglycine, cyclohexylalanine, β-alanine, fluoro-amino acids,designer amino acids such as β-methyl amino acids, Cα-methyl aminoacids, Nα-methyl amino acids, PNA's and amino acid analogs in general.Furthermore, the amino acid can be D or L isoform.

The fragments may or may not possess similar functionality as matureMtrE proteins. In one embodiment, the fragments of the present inventionpossess at least one known function of an MtrE protein. In anotherembodiment, the fragments of the present invention are antigenic. Inanother embodiment, the fragments of the present invention areimmunogenic. For example, the MtrE-derived polypeptides of the inventionmay be immunologically cross-reactive and may be capable of eliciting inan animal an immune response to N. gonorrhoeae, N. gonorrhoeae infectedcells or antigen presenting cells expressing N. gonorrhoeae antigensand/or are able to be bound by anti-MtrE antibodies. As used herein theterm “antigenic” refers to a substance such as a peptide or nucleic acidto which an antibody or T-cell receptor specifically binds. The term“immunogenic” refers to a peptides ability to elicit at least a partialimmune response, including but not limited to, production ofneutralizing antibodies, recruitment of helper T cells, productioncytokines and other inflammatory mediators, when administered to anorganism. One of skill in the art readily understands the differencebetween an “antigenic response” and an “immunogenic response” as usedherein.

The antigenicity and/or immunogenicity of the peptides or fragmentsdescribed herein may or may not necessarily require the use of anadjuvant or combination of adjuvants such as, but not limited to, alum,aluminum phosphate, aluminum hydroxide, squalene, oil-based adjuvants,virosomes, QS21, MF59, interleukin 12 (IL-12), CpG, small molecule mastcell activator (MP7), TLR7 imidazoquinoline ligand 3M-019, resquimod(R848), N-acetyl-muramyl-L-threonyl-D-isoglutamine (thr-MDP),N-acetyl-nor-muramyl-L-alanyl-D-isoglutamine (CGP 11637, referred to asnor-MDP),N-acetylmuramyl-L-alanyl-D-isoglutaminyl-L-alanine-2-(1′-2′-dip-almitoyl-sn-glycero-3hydroxyphosphoryloxy)-ethylamine (CGP 19835A, referred to as MTP-PE),and RIBI, which contains three components extracted from bacteria,monophosphoryl lipid A, trehalose dimycolate and cell wall skeleton(MPL+TDM+CWS) in a 2% squalene/Tween 80. Tables IV and V provideinformation on adjuvants that may be useful. Table IV shows possibleadjuvants and their properties. These adjuvants may be used alone or incombination to test their ability to augment the immune response towardsN. gonorrhoeae and MtrE. These adjuvants are defined by their ability todrive a Th1 or Th2 response. Table V shows adjuvants and adjuvantcombinations of mice immunized with MtrE. The geometric mean of thefinal serum titer is shown. MtrE-specific antibody was detected viaELISA.

TABLE IV Adjuvant Properties CT Potent mucosal adjuvant (Th2 response)CpG TLR 9 agonist (Th1 response) MplA TLR 4 agonist (Th1 response) R 848TLR 7/8 agonist (Th1 response) IL-12 Pro-inflammatory cytokine (Th1response) CT + CpG Th2 + Th1 response CT + MplA Th2 + Th1 response CT +R 848 Th2 + Th1 response CT + IL-12 Th2 + Th1 response CpG + MplA Th1response CpG + R 848 Th1 response CpG + Pam3CSK4 Th1 response

TABLE V Adjuvant MtrE-Specific Titer CT 228,209 CpG 262,144 R 848 32,768Pam3CSK4 155,871 MPLA 41,285 CpG + R 848 131,072 CpG + Pam3CSK4 92,681CpG + MPLA 131,072

As used herein, the terms “correspond(s) to” and “corresponding to,” asthey relate to sequence alignment, are intended to mean enumeratedpositions within a reference protein, e.g., wild-type MtrE, and thosepositions in a modified MtrE that align with the positions on thereference protein. Thus, when the amino acid sequence of a subjectprotein is aligned with the amino acid sequence of a reference protein,the amino acids in the subject sequence that “correspond to” certainenumerated positions of the reference sequence are those that align withthese positions of the reference sequence, but are not necessarily inthese exact numerical positions of the reference sequence. Methods foraligning sequences for determining corresponding amino acids betweensequences are described herein.

The amino acid residues of the MtrE proteins of the present inventionmay or may not be modified such as, but not limited to, addition offunctional or non-functional groups such a but not limited to, acetylgroups, hydroxyl groups, carboxyl groups, carbohydrate groups(glycosylation), phosphate groups and lipid groups to name a few. Any ofnumerous chemical modifications may be carried out by known techniques,including but not limited to, specific chemical cleavage by cyanogenbromide, trypsin, chymotrypsin, papain, V8 protease, NaBH₄, acetylation,formylation, oxidation, reduction, metabolic synthesis in the presenceof tunicamycin, etc.

The MtrE proteins of the present invention may or may not containadditional elements that, for example, may include but are not limitedto regions to facilitate purification. For example, “histidine tags”(“his tags”) or “lysine tags” may be appended or “fused” to the MtrEproteins to create “MtrE fusion proteins.” Examples of histidine tagsinclude, but are not limited to hexaH, heptaH and hexaHN. Examples oflysine tags include, but are not limited to pentaL, heptaL and FLAG.Such regions may be removed prior to final preparation of the MtrEproteins. Other examples of a second fusion peptide include, but are notlimited to, glutathione S-transferase (GST) and alkaline phosphatase(AP).

The addition of peptide moieties to MtrE proteins, whether to engendersecretion or excretion, to improve stability and to facilitatepurification or translocation, among others, is a familiar and routinetechnique in the art and may include modifying amino acids at theterminus to accommodate the tags. For example the N-terminus amino acidmay be modified to, for example, arginine and/or serine to accommodate atag. Of course, the amino acid residues of the C-terminus may also bemodified to accommodate tags. One particularly useful fusion proteincomprises a heterologous region from immunoglobulin that can be usedsolubilize proteins.

Other types of fusion proteins provided by the present invention includebut are not limited to, fusions with secretion signals and otherheterologous functional regions. Thus, for instance, a region ofadditional amino acids, particularly charged amino acids, may be addedto the N-terminus of the MtrE proteins to improve stability andpersistence in the host cell, during purification or during subsequenthandling and storage.

Another particular example of fusion polypeptides of the inventionincludes an MtrE polypeptide, fragment or variant thereof fused to apolypeptide having adjuvant activity, such as the subunit B of eithercholera toxin or E. coli heat labile toxin. Another particular exampleof a fusion polypeptide encompassed by the invention includes an MtrEpolypeptide fused to a cytokine, such as, but not limited to, IL-2,IL-4, IL-10, IL-12, or interferon. An MtrE polypeptide of the inventioncan be fused to the N- or C-terminal end of a polypeptide havingadjuvant activity. Alternatively, an MtrE polypeptide of the inventioncan be fused within the amino acid sequence of the polypeptide havingadjuvant activity.

Also, in one embodiment, the MtrE polypeptides, and fusions thereof, ofmay comprise sequences that form one or more epitopes of a native N.gonorrhoeae MtrE polypeptide that elicit bactericidal or opsonizingantibodies and/or T-cells. Such MtrE polypeptides may be identified bytheir ability to generate antibodies and/or T-cells that kill cellsinfected with N. gonorrhoeae cells.

The MtrE proteins and MtrE fusion proteins of the current invention canbe recovered and purified from recombinant cell cultures by well-knownmethods including, but not limited to, ammonium sulfate or ethanolprecipitation, acid extraction, anion or cation exchange chromatography,phosphocellulose chromatography, hydrophobic interaction chromatography,affinity chromatography, e.g., immobilized metal affinity chromatography(IMAC), hydroxylapatite chromatography and lectin chromatography. Highperformance liquid chromatography (“HPLC”) may also be employed forpurification. Well-known techniques for refolding protein may beemployed to regenerate active conformation when the MtrE protein isdenatured during isolation and/or purification.

If desired, the individual amino acid sequences of the components of thefusion proteins can be produced and joined by a linker. Suitable peptidelinker sequences may be chosen based on the following factors: (1) theirability to adopt a flexible extended conformation, (2) their ability toadopt a secondary structure that could interact with functional epitopesof the first and second polypeptides, (3) the lack of hydrophobic orcharged residues that might react with the polypeptide functionalepitopes, (4) the ability to increase solubility, and (5) the ability toincrease sensitivity to processing by antigen-presenting cells. Suchlinkers can be any amino acid sequence or other appropriate link orjoining agent.

Linkers useful in the invention include linkers comprising a chargedamino acid pair such as KK or RR, linkers sensitive to cathepsin and/orother trypsin-like enzymes, thrombin or Factor X_(a), or linkers whichresult in an increase in solubility of the polypeptide. Specificexamples of linkers include those linkers that contain Gly, Asn and Serresidues. Amino acid sequences which may be usefully employed as linkersinclude those disclosed in Maratea et al., Gene 40:39-46 (1985), Murphyet al., Proc. Nat. Acad Sci USA, 83:8258-8562 (1986), U.S. Pat. Nos.4,935,233 and 4,751,180, all of which are incorporated by reference. Thelinker sequence may be from 1 to about 150 amino acids in length or evenlonger.

The MtrE proteins and fusions thereof include but are not limited toproducts of chemical synthetic procedures and products produced byrecombinant techniques from a prokaryotic or eukaryotic host, including,for example, bacterial, yeast, higher plant, insect and mammalian cells.Depending upon the host employed in a recombinant production procedure,the MtrE proteins and fusions thereof of the present invention may beglycosylated or may be non-glycosylated. In addition, the MtrE proteinsand fusions thereof of the present invention may also include an initialmodified methionine residue, in some cases as a result of host-mediatedprocesses.

The invention is not limited to the source of the MtrE proteins orfusions thereof. One source, for example, is a protein preparation froma gene expression system (such as E. coli) engineered to express acloned sequence encoding an MtrE polypeptide or fusion thereof.

The MtrE proteins and/or fusions thereof can be isolated and purifiedfrom the source material using any biochemical technique and approachwell known to those skilled in the art. In one approach, N. gonorrhoeaecellular envelope is obtained by standard techniques and inner membrane,periplasmic and outer membrane proteins are solubilized using asolubilizing compound such as a detergent or hypotonic solution. Oneuseful detergent solution is one containing octyl glucopyranoside (OG),sarkosyl n-Dodecyl-β-D-Maltopyranosid or TRITON X100™ (t-octylphenoxy-polyethoxy-ethanol). One example of a solubilizing hypotonicsolution is one containing LiCl, and the MtrE polypeptide may be in thesolubilized fraction. Cellular debris and insoluble material in theextract are separated and removed, for example by centrifugation. Thepolypeptides in the extract are concentrated, incubated inSDS-containing Laemmli gel sample buffer at 100° C. for 5 minutes andthen fractionated by electrophoresis in a denaturing sodiumdodecylsulfate (SDS) polyacrylamide gel from about 6% to about 12%, withor without a reducing agent. The band or fraction identified as a MtrEpolypeptide may then be purified directly from the fraction or gel slicecontaining the MtrE polypeptide.

Another method of purifying MtrE polypeptide or fusion thereof is byaffinity chromatography using anti-MtrE antibodies. The affinitychromatography may be carried out using either polyclonal or monoclonalanti-MtrE antibodies. The antibodies can be covalently linked to agarosegels activated by cyanogen bromide or succinamide esters (Affi-Gel,BioRad, Inc.) or by other methods known to those skilled in the art. Theprotein extract can be loaded on the top of the gel and can be left incontact with the gel for a period of time and under standard reactionconditions sufficient for MtrE polypeptide to bind to the antibody. Thesolid support may be a material used in a chromatographic column. Theaffinity gel is washed to remove other proteins and cell materials notbound by the anti-MtrE antibody. The MtrE polypeptide is then removedfrom the antibody to recover the MtrE polypeptide in isolated orpurified form.

An MtrE polypeptide and/or fusion thereof can be produced by chemicaland/or enzymatic cleavage or degradation of an isolated or purified MtrEpolypeptide. An MtrE polypeptide can also be chemically synthesizedbased on the known amino acid sequence of the MtrE polypeptide and, inthe case of a chimeric or fusion polypeptide, the amino acid sequence ofthe heterologous polypeptide, by methods well known in the art.

An MtrE polypeptide and/or fusion thereof can also be produced in a geneexpression system expressing a recombinant nucleic acid constructcomprising a sequence encoding an MtrE polypeptide of the presentinvention. The nucleotide sequences encoding polypeptides of theinvention may be synthesized, and/or cloned, and expressed according totechniques well known to those skilled in the art. See, for example,Sambrook, et al., 1989, Molecular Cloning, A Laboratory Manual, Vols.1-3, Cold Spring Harbor Press, NY, which is incorporated by reference inits entirety.

If desirable, the MtrE polypeptides of the invention may be furtherpurified using standard protein or peptide purification techniquesincluding but not limited to, electrophoresis, centrifugation, gelfiltration, precipitation, dialysis, chromatography (including ionexchange chromatography, affinity chromatography, immunoadsorbentaffinity chromatography, dye-binding chromatography, size exclusionchromatography, hydroxyapatite chromatography, reverse-phase highperformance liquid chromatography, and gel permeation high performanceliquid chromatography), isoelectric focusing, and variations andcombinations thereof.

One or more of these techniques may be employed sequentially in aprocedure designed to isolate and/or purify the MtrE polypeptides of thepresent invention according to its/their physical or chemicalcharacteristics. These characteristics include the hydrophobicity,charge, binding capability, and molecular weight of the proteins. Thevarious fractions of materials obtained after each technique are testedfor binding to, for example, the anti-MtrE antibodies or for functionalactivity. Those fractions showing such test activity are then pooled andsubjected to the next technique in the sequential procedure, and the newfractions are tested again. The process can be repeated as often asdesired.

The present invention provides antibodies that specifically bind an MtrEpolypeptide and/or an epitope on N. gonorrhoeae. For the production ofsuch antibodies, isolated or purified preparations of an MtrEpolypeptide of the present invention can be used as an immunogen in animmunogenic composition. The same immunogen can be used to immunize micefor the production of hybridoma lines that produce monoclonal anti-MtrEantibodies. In particular embodiments, the immunogen is an isolated orpurified MtrE polypeptide of the present invention.

In other embodiments, the MtrE polypeptides of the present invention areused as immunogens. The peptides may be produced by protease digestion,chemical cleavage of isolated or purified MtrE polypeptide, chemicalsynthesis or by recombinant expression, after which they are thenisolated or purified. Such isolated or purified peptides can be useddirectly as immunogens. In particular embodiments, useful peptidefragments are 8 or more amino acids in length.

Useful immunogens may also comprise such MtrE peptides conjugated to acarrier molecule, such as a carrier protein. Carrier proteins may be anycommonly used in immunology, include, but are not limited to, bovineserum albumin (BSA), chicken albumin, keyhole limpet hemocyanin (KLH),tetanus toxoid, synthetic T cell epitopes and the like.

In one embodiment, the anti-MtrE antibodies are monoclonal antibodies.In another embodiment, the anti-MtrE antibodies are polyclonalantibodies.

In further embodiments, useful immunogens for eliciting antibodies ofthe invention comprise mixtures of two or more of any of theabove-mentioned individual immunogens.

Immunization of animals with the immunogens described herein, forexample in humans, rabbits, rats, ferrets, mice, sheep, goats, cows orhorses, can be performed following procedures well known to thoseskilled in the art, for purposes of obtaining antisera containingpolyclonal antibodies or hybridoma lines secreting monoclonalantibodies.

Monoclonal antibodies can be prepared by standard techniques, given theteachings contained herein. Such techniques are disclosed, for example,in U.S. Pat. Nos. 4,271,145 and 4,196,265, which are incorporated byreference. Briefly, an animal is immunized with the immunogen.Hybridomas are prepared by fusing spleen cells from the immunized animalwith myeloma cells. The fusion products are screened for those producingantibodies that bind to the immunogen. The positive hybridomas clonesare isolated, and the monoclonal antibodies are recovered from thoseclones.

Immunization regimens for production of both polyclonal and monoclonalantibodies are well known in the art. The immunogen may be injected byany of a number of routes, including subcutaneous, intravenous,intraperitoneal, intradermal, intramuscular, mucosal (e.g., nasal,vaginal, rectal), or a combination of these. The immunogen may beinjected in soluble form, aggregate form, attached to a physicalcarrier, or mixed with an adjuvant, using methods and materials wellknown in the art. The antisera and antibodies may be purified usingcolumn chromatography methods well known to those of skill in the art.

The antibodies may also be used as probes for identifying clones inexpression libraries that have or may have inserts encoding one or moreMtrE polypeptides described herein. The antibodies or MtrE polypeptidesmay also be used in immunoassays, e.g., ELISA, RIA, Western Blots, tospecifically detect and/or quantitate N. gonorrhoeae or anti-N.gonorrhoeae antibody in biological specimens. The anti-MtrE antibodiesof the invention specifically bind it MtrE from N. gonorrhoeae and canbe used to diagnose N. gonorrhoeae infections.

The antibodies of the invention, including but not limited to those thatare cytotoxic, cytostatic, or neutralizing, may also be used in passiveimmunization to prevent or attenuate N. gonorrhoeae infections ofanimals, including humans. As used herein, a cytotoxic antibody is onethat enhances opsonization and/or complement killing of the bacteriumbound by the antibody. As used herein, neutralizing antibody is one thatreduces the infectivity of the N. gonorrhoeae and/or blocks binding ofN. gonorrhoeae to a target cell. An effective concentration ofpolyclonal or monoclonal antibodies raised against the immunogens of theinvention may be administered to a host to achieve such effects. Theexact concentration of the antibodies administered will vary accordingto each specific antibody preparation, but may be determined usingstandard techniques well known to those of ordinary skill in the art.Administration of the antibodies may be accomplished using a variety oftechniques, including but not limited to those described herein.

Another aspect of the invention is directed to antisera raised againstan antigenic or immunogenic composition of the invention, and antibodiespresent in the antisera that specifically bind an MtrE protein of thepresent invention. In one specific embodiment, the antibodies orantibody fragments described herein bind to peptides with an amino acidsequence of SEQ ID NO:2 or SEQ ID NO:3.

The term “antibodies” is intended to include all forms, such as but notlimited to polyclonal, monoclonal, purified IgG, IgM, or IgA antibodiesand fragments thereof, including but not limited to antigen bindingfragments such as Fv, single chain Fv (scFv), F(ab)₂, Fab, and F(ab)′fragments, single chain antibodies as disclosed in U.S. Pat. No.4,946,778 (incorporated by reference), as well as complementarydetermining regions (CDR) as disclosed in Verhoeyen and Winter, inMolecular Immunology 2ed., by B. D. Hames and D. M. Glover, IRL Press,Oxford University Press, 1996, at pp. 283-325 (incorporated byreference) etc.

A further aspect of the invention are chimeric or humanized antibodies(Morrison et al., 1984, Proc. Nat'l Acad. Sci. USA 81:6851; Reichmann etal. Nature 332:323: U.S. Pat. Nos. 5,225,539; 5,585,089; and U.S. Pat.No. 5,530,101; Neuberger et al., 1984, Nature 81:6851 Riechmann et al.,1988, Nature 332:323; U.S. Pat. Nos. 5,225,539; 5,585,089; and5,530,101, all of which are incorporated by reference) in which one ormore of the antigen binding regions of the anti-MtrE antibody isintroduced into the framework region of a heterologous (e.g. human)antibody. The chimeric or humanized antibodies of the invention are lessantigenic in humans than non-human antibodies but have the desiredantigen binding and other activities, including but not limited toneutralizing activity, cytotoxic activity, opsonizing activity orprotective activity.

In one aspect of the invention, the antibodies of the invention arehuman antibodies. Human antibodies may be isolated, for example, fromhuman immunoglobulin libraries (see, e.g., PCT publications WO 98/46645,WO 98/50433, WO 98/24893, WO 98/16054, WO 96/34096, WO 96/33735, and WO91/10741, all of which are incorporated by reference) by, for example,phage display techniques (see, e.g., Brinkman et al., J. Immunol.Methods 182:41-50 (1995); Ames et al., J. Immunol. Methods 184:177-186(1995); Kettleborough et al., Eur. J. Immunol. 24:952-958 (1994); Persicet al., Gene 187 9-18 (1997); Burton et al., Advances in Immunology57:191-280 (1994); PCT application No. PCT/GB91/01134; PCT publicationsWO 90/02809; WO 91/10737; WO 92/01047; WO 92/18619; WO 93/11236; WO95/15982; WO 95/20401; and U.S. Pat. Nos. 5,698,426; 5,223,409;5,403,484; 5,580,717; 5,427,908; 5,750,753; 5,821,047; 5,571,698;5,427,908; 5,516,637; 5,780,225; 5,658,727; 5,733,743 and 5,969,108;each of which is incorporated herein by reference in its entirety. Humanantibodies may also be generated from animals transgenic for one or morehuman immunoglobulin and that do not express endogenous immunoglobulins,see, e.g., U.S. Pat. No. 5,939,598, which is incorporated by reference.

A further aspect of the invention is T-cells specific for N.gonorrhoeae, N. gonorrhoeae infected cells or antigen presenting cellsdisplaying N. gonorrhoeae antigens. T-cell preparations enriched forT-cells specific for the MtrE polypeptides of the present invention canbe produced or isolated by methods known in the art

The invention also provides polynucleotides that code for the isolatedMtrE proteins disclosed herein. The nucleic acids of the invention canbe DNA or RNA, for example, mRNA. The nucleic acid molecules can bedouble-stranded or single-stranded; single stranded RNA or DNA can bethe coding, or sense, strand or the non-coding, or antisense, strand. Inparticular, the nucleic acids may encode any of the MtrE proteinsdisclosed herein, as well as variants thereof. Of course, the nucleicacids of the present invention may encode additional elements, such ashis tags and the like. For example, the nucleic acids of the inventionwould include those that encode any of the MtrE proteins and variantsthereof that are also contain a glutathione-S-transferase (GST) fusionprotein, poly-histidine (e.g., Hiss), poly-HN, poly-lysine, etc. Ifdesired, the nucleotide sequences can include additional non-codingsequences such as non-coding 3′ and 5′ sequences (including regulatorysequences, for example).

In another specific embodiment, the invention provides nucleic acidsthat are hybridizable to a nucleic acid encoding an MtrE polypeptide ofthe present invention. Various other stringency conditions that promotenucleic acid hybridization can be used. For example, hybridization in6×SSC at about 45° C., followed by washing in 2×SSC at 50° C. may beused. Alternatively, the salt concentration in the wash step can rangefrom low stringency of about 5×SSC at 50° C., to moderate stringency ofabout 2×SSC at 50° C., to high stringency of about 0.2×SSC at 50° C. Inaddition, the temperature of the wash step can be increased from lowstringency conditions at room temperature, to moderately stringentconditions at about 42° C., to high stringency conditions at about 65°C. Other conditions include, but are not limited to, hybridizing at 68°C. in 0.5M NaHPO₄ (pH7.2)/1 mM EDTA/7% SDS, or hybridization in 50%formamide/0.25M NaHPO₄ (pH 7.2)/0.25 M NaCl/1 mM EDTA/7% SDS; followedby washing in 40 mM NaHPO₄ (pH 7.2)/1 mM EDTA/5% SDS at 42° C. or in 40mM NaHPO₄ (pH7.2)/1 mM EDTA/1% SDS at 50° C. Both temperature and saltmay be varied, or alternatively, one or the other variable may remainconstant while the other is changed.

Low, moderate and high stringency conditions are well known to those ofskill in the art, and will vary predictably depending on the basecomposition of the particular nucleic acid sequence and on the specificorganism from which the nucleic acid sequence is derived. For guidanceregarding such conditions see, for example, Sambrook et al., 1989,Molecular Cloning, A Laboratory Manual, Second Edition, Cold SpringHarbor Press, N.Y and Ausubel et al., 1989, Current Protocols inMolecular Biology, Green Publishing Associates and Wiley Interscience,N.Y.

Nucleic acids encoding MtrE polypeptides of the present invention may beproduced by methods well known in the art. In one aspect, nucleic acidsencoding the MtrE polypeptides can be derived from MtrE polypeptidecoding sequences by recombinant DNA methods known in the art. Forexample, the coding sequence of an MtrE polypeptide may be alteredcreating amino acid substitutions that will not affect theimmunogenicity of the MtrE polypeptide or which may improve itsimmunogenicity, such as conservative or semi-conservative substitutionsas described above. Various methods may be used, including but notlimited to, oligonucleotide directed, site specific mutagenesis. Thisand other techniques known in the art may be used to create single ormultiple mutations, such as replacements, insertions, deletions, andtranspositions, for example, as described in Botstein and Shortie, 1985,Science 229:1193-1210, which is incorporated by reference.

In one embodiment, the nucleic acids encoding the MtrE proteins aresynthetic nucleic acids in which the codons have been optimized forincreased expression in the host cell in which it is produced. Thedegeneracy of the genetic code permits variations of the nucleotidesequence, while still producing a polypeptide having the identical aminoacid sequence as the polypeptide encoded by the native DNA sequence. Thefrequency of individual synonymous codons for amino acids varies widelyfrom genome to genome among eukaryotes and prokaryotes. Thesedifferences in codon choice patterns appear to contribute to the overallexpression levels of individual genes by modulating peptide elongationrates. For this reason it may be desirable and useful to design nucleicacid molecules intended for a particular expression system where thecodon frequencies reflect the tRNA frequencies of the host cell ororganism in which the protein is expressed. Native codons are exchangedfor codons of highly expressed genes in the host cells. For instance,the nucleic acid molecule can be optimized for expression of the encodedprotein in bacterial cells (e.g., E. coli), yeast (e.g., Pichia), insectcells (e.g., Drosophila), or mammalian cells or animals (e.g., human,sheep, bovine or mouse cells or animals).

Restriction enzyme sites critical for gene synthesis and DNAmanipulation are preserved or destroyed to facilitate nucleic acid andvector construction and expression of the encoded protein. Inconstructing the synthetic genes of the invention it may be desirable toavoid CpG sequences as these sequences may cause gene silencing. Thecodon optimized sequence can be synthesized and assembled and insertedinto an appropriate expression vector using conventional techniques wellknown to those of skill in the art.

In one particular embodiment, a synthetic nucleic acid encoding an MtrEprotein of the present invention comprises at least one codonsubstitution in which non-preferred or less preferred codon in thenatural gene encoding the protein has been replaced by a preferred codonencoding the same amino acid. For instance in humans the preferredcodons are: Ala (GCC); Arg (CGC); Asn (AAC); Asp (GAC); Cys (TGC); Gln(CAG); Gly (GGC); His (CAC); Ile (ATC); Leu (CTG); Lys (AAG); Pro(CCC);Phe (TTC); Ser (AGC); Thr (ACC); Tyr (TAC); and Val (GTG). Lesspreferred codons are: Gly (GGG); Ile (ATT); Leu (CTC); Ser (TCC); Val(GTC); and Arg (AGG). In general, the degree of preference of aparticular codon is indicated by the prevalence of the codon in highlyexpressed genes. Replacing a codon with another codon that is moreprevalent in highly expressed human genes will generally increaseexpression of the gene in mammalian cells. Accordingly, the inventionincludes replacing a less preferred codon with a preferred codon as wellas replacing a non-preferred codon with a preferred or less preferredcodon.

Further, nucleic acids containing the MtrE polypeptide coding sequencesmay be truncated by restriction enzyme or exonuclease digestions.Heterologous coding sequences may be added to the MtrE polypeptidecoding sequences by ligation or PCR amplification. Moreover, DNAencoding the whole or a part of MtrE polypeptide of the presentinvention may be synthesized chemically or using PCR amplification basedon the known or deduced amino acid sequence of the MtrE polypeptide andany desired alterations to that sequence.

The identified and isolated DNA encoding the MtrE polypeptides of thepresent invention can be inserted into an appropriate cloning vector. Alarge number of vector-host systems known in the art may be used. Theterm “host” or “host cell” as used herein refers to either in vivo in ananimal or in vitro in mammalian cell cultures.

The present invention also comprises vectors containing the nucleicacids encoding the MtrE proteins of the present invention. As usedherein, a “vector” may be any of a number of nucleic acids into which adesired sequence may be inserted by restriction and ligation fortransport between different genetic environments or for expression in ahost cell. Vectors are typically composed of DNA although RNA vectorsare also available. Vectors include, but are not limited to, plasmidsand phagemids. A cloning vector is one which is able to replicate in ahost cell, and which is further characterized by one or moreendonuclease restriction sites at which the vector may be cut in adeterminable fashion and into which a desired DNA sequence may beligated such that the new recombinant vector retains its ability toreplicate in the host cell. An expression vector is one into which adesired DNA sequence may be inserted by restriction and ligation suchthat it is operably joined to regulatory sequences and may be expressedas an RNA transcript. Vectors may further contain one or more markersequences suitable for use in the identification and selection of cellswhich have been transformed or transfected with the vector. Markersinclude, for example, genes encoding proteins which increase or decreaseeither resistance or sensitivity to antibiotics or other compounds,genes which encode enzymes whose activities are detectable by standardassays known in the art (e.g., β-galactosidase or alkaline phosphatase),and genes which visibly affect the phenotype of transformed ortransfected cells, hosts, colonies or plaques. Examples of vectorsinclude but are not limited to those capable of autonomous replicationand expression of the structural gene products present in the DNAsegments to which they are operably joined.

In certain respects, the vectors to be used are those for expression ofpolynucleotides and proteins of the present invention. Generally, suchvectors comprise cis-acting control regions effective for expression ina host operatively linked to the polynucleotide to be expressed.Appropriate trans-acting factors are supplied by the host, supplied by acomplementing vector or supplied by the vector itself upon introductioninto the host.

A great variety of expression vectors can be used to express theproteins of the invention. Such vectors include chromosomal, episomaland virus-derived vectors, e.g., vectors derived from bacterialplasmids, from bacteriophage, from yeast episomes, from yeastchromosomal elements, from viruses such as adeno-associated virus,lentivirus, baculoviruses, papova viruses, such as SV40, vacciniaviruses, adenoviruses, fowl pox viruses, pseudorabies viruses andretroviruses, and vectors derived from combinations thereof, such asthose derived from plasmid and bacteriophage genetic elements, such ascosmids and phagemids. All may be used for expression in accordance withthis aspect of the present invention. Generally, any vector suitable tomaintain, propagate or the fusion proteins in a host may be used forexpression in this regard.

The DNA sequence in the expression vector is generally operably linkedto appropriate expression control sequence(s) including, for instance, apromoter to direct mRNA transcription. Representatives of such promotersinclude, but are not limited to, the phage lambda PL promoter, the E.coli lac, trp and tac promoters, HIV promoters, the SV40 early and latepromoters and promoters of retroviral LTRs, to name just a few of thewell-known promoters. In general, expression constructs will containsites for transcription, initiation and termination and, in thetranscribed region, a ribosome binding site for translation. The codingportion of the mature transcripts expressed by the constructs willinclude a translation initiating AUG at the beginning and a terminationcodon (UAA, UGA or UAG) appropriately positioned at the end of thepolypeptide to be translated.

In addition, the constructs may contain control regions that regulate,as well as engender expression. Generally, such regions will operate bycontrolling transcription, such as repressor binding sites andenhancers, among others.

Vectors for propagation and expression generally will include selectablemarkers. Such markers also may be suitable for amplification or thevectors may contain additional markers for this purpose. In this regard,the expression vectors may contain one or more selectable marker genesto provide a phenotypic trait for selection of transformed host cells.Preferred markers include dihydrofolate reductase or neomycin resistancefor eukaryotic cell culture, and tetracycline, kanamycin or ampicillinresistance genes for culturing E. coli and other bacteria.

Promoter/enhancer elements which may be used to control expression ofinserted sequences include, but are not limited to the SV40 earlypromoter region (Bernoist and Chambon, 1981, Nature 290:304-310), thepromoter contained in the 3′ long terminal repeat of Rous sarcoma virus(Yamamoto et al., 1980, Cell 22:787-797), the herpes thymidine kinasepromoter (Wagner et al., 1981, Proc. Natl. Acad. Sci. U.S.A.78:1441-1445), the regulatory sequences of the metallothionein gene(Brinster et al., 1982, Nature 296:39-42) for expression in animalcells, the promoters of lactamase (Villa-Kamaroff et al., 1978, Proc.Natl. Acad. Sci. U.S.A. 75:3727-3731), tac (DeBoer et al., 1983, Proc.Natl. Acad. Sci. U.S.A. 80:21-25), or trc for expression in bacterialcells (see also “Useful proteins from recombinant bacteria” inScientific American, 1980, 242:74-94), the nopaline synthetase promoterregion or the cauliflower mosaic virus 35S RNA promoter (Gardner et al.,1981, Nucl. Acids Res. 9:2871), and the promoter of the photosyntheticenzyme ribulose biphosphate carboxylase (Herrera-Estrella et al., 1984,Nature 310:115-120) for expression in plant cells; Gal4 promoter, theADC (alcohol dehydrogenase) promoter, PGK (phosphoglycerol kinase)promoter, alkaline phosphatase promoter for expression in yeast or otherfungi.

Depending on the host-vector system utilized, any one of a number ofsuitable transcription and translation elements may be used. In oneembodiment, a fusion protein comprising an MtrE polypeptide of thepresent invention and a pre and/or pro sequence of the host cell isexpressed. In other embodiments, a fusion protein comprising an MtrEprotein of the present invention fused with, for example, an affinitypurification peptide, including but not limited to, maltose bindingprotein, glutathione-S-transferase, thioredoxin or histidine tag, isexpressed. In additional embodiments, a chimeric protein comprising anMtrE polypeptide of the present invention and a useful immunogenicpeptide or protein is expressed.

Any method known in the art for inserting DNA fragments into a vectormay be used to construct expression vectors containing an MtrEpolypeptide encoding nucleic acid molecule comprising appropriatetranscriptional/translational control signals and the polypeptide codingsequences. These methods may include in vitro recombinant DNA andsynthetic techniques and in vivo recombination.

Methods of introducing exogenous DNA into yeast hosts include either thetransformation of spheroplasts or of intact yeast cells treated withalkali cations. Transformation procedures usually vary with the yeastspecies to be transformed. See e.g., Kurtz et al. (1986) Mol. Cell.Biol. 6:142; Kunze et al. (1985) J. Basic Microbiol. 25:141; forCandida, Gleeson et al. (1986) J. Gen. Microbiol. 132:3459; Roggenkampet al. (1986) Mol. Gen. Genet. 202:302; for Hansenula; Das et al. (1984)J. Bacteriol. 158:1165; De Louvencourt et al. (1983) J. Bacteriol.154:1165; Van den Berg et al. (1990) Bio/Technology 8:135; forKluyveromyces; Cregg et al. (1985) Mol. Cell. Biol. 5:3376; Kunze et al.(1985) J. Basic Microbiol. 25:141; U.S. Pat. Nos. 4,837,148 and4,929,555; for Pichia; Hinnen et al. (1978) Proc. Natl. Acad. Sci. USA75; 1929; Ito et al. (1983) J. Bacteriol. 153:163; for Saccharomyces;Beach et al. (1981) Nature 300:706; for Schizosaccharomyces; Davidow etal. (1985) Curr. Genet. 10:39.

Commercially available vectors for expressing heterologous proteins inbacterial hosts include but are not limited to pZERO, pTrc99A, pUC19,pUC18, pKK223-3, pEX1, pCAL, pET, pSPUTK, pTrxFus, pFastBac, pThioHis,pTrcHis, pTrcHis2, and pLEx. For example, the phage in lambda GEM™-11may be utilized in making recombinant phage vectors which can be used totransform host cells, such as E. coli LE392. In a preferred embodiment,the vector is pQE30 or pBAD/ThioE, which can be used transform hostcells, such as E. coli.

Expression and transformation vectors for transformation into many yeaststrains are available. For example, expression vectors have beendeveloped for, the following yeasts: Candida albicans, Kurtz, et al.(1986) Mol. Cell. Biol. 6:142; Candida maltosa, Kunze, et al. (1985) J.Basic Microbiol. 25:141; Hansenula po/ymorpha, Gleeson, et al. (1986) J.Gen. Microbiol. 132:3459; Roggenkamp et al. (1986) Mol. Gen. Genet.202:302; Kluyveromyces fragilis, Das, et al. (1984) J. Bacteriol.158:1165; Kluyveromyces lactis, De Louvencourt et al. (1983) J.Bacteriol. 154:737; Van den Berg, et al. (1990) Bio/Technology 8:135;Pichia quillerimondii, Kunze et al. (1985) J. Basic Microbiol. 25:141;Pichia pastoris, Cregg, et al. (1985) Mol. Cell. Biol. 5:3376, U.S. Pat.Nos. 4,837,148 and 4,929,555; Saccharomyces cerevisiae, Hinnen et al.(1978) Proc. Natl. Acad. Sci. USA 75:1929, Ito et al. (1983) J.Bacteriol. 153:163; Schizosaccharomyces pombe, Beach et al. (1981)Nature 300:706; and Yarrowia lipolytica, Davidow, et al. (1985) Curr.Genet. 10:380-471, Gaillardin, et al. (1985) Curr. Genet. 10:49.

The invention also provides for host cells comprising the nucleic acidsand vectors described herein. A variety of host-vector systems may beutilized to express the polypeptide-coding sequence. These include butare not limited to mammalian cell systems infected with virus (e.g.,vaccinia virus, adenoviris, etc.); insect cell systems infected withvirus (e.g., baculovirus); microorganisms such as yeast containing yeastvectors, or bacteria transformed with bacteriophage DNA, plasmid DNA, orcosmid DNA, plant cells or transgenic plants.

Hosts that are appropriate for expression of nucleic acid molecules ofthe present invention, fragments, analogues or variants thereof, mayinclude E. coli, Bacillus species, Haemophilus, fungi, yeast, such asSaccharomyces, Pichia, Bordetella, or Candida, or the baculovirusexpression system.

In addition, a host cell strain may be chosen which modulates theexpression of the inserted sequences, or modifies and processes the geneproduct in the specific fashion desired. Expression from certainpromoters can be elevated in the presence of certain inducers; thus,expression of the genetically engineered MtrE polypeptides may becontrolled. Furthermore, different host cells have characteristic andspecific mechanisms for the translational and post-translationalprocessing and modification of proteins. Appropriate cell lines or hostsystems can be chosen to ensure the desired modification and processingof the foreign protein expressed.

Once a suitable host system and growth conditions are established,recombinant expression vectors can be propagated and prepared inquantity. Upon expression, a recombinant polypeptide of the invention isproduced and can be recovered in a substantially purified from the cellpaste, the cell extract or from the supernatant after centrifugation ofthe recombinant cell culture using techniques well known in the art.

For instance, the recombinant polypeptide can be purified byantibody-based affinity purification, preparative gel electrophoresis,or affinity purification using tags (e.g., 6× histidine tag) included inthe recombinant polypeptide.

The present invention is also directed to methods of producing isolatedMtrE proteins, with the method comprising culturing a host cellharboring a vector coding for the MtrE protein in culture conditions inwhich expression of the MtrE protein from the vector occurs in the host,and purifying the MtrE protein from the cell culture.

The present invention also directed to pharmaceutical compositioncomprising the isolated MtrE proteins of the present invention.

The present invention also provides therapeutic and prophylacticcompositions, which may be antigenic compositions, and immunogeniccompositions, including vaccines, for use in the treatment or prevention(reducing the likelihood) of N. gonorrhoeae infections in human subjects(patients). The immunogenic compositions include vaccines for use inhumans. The antigenic and immunogenic, compositions of the presentinvention can be prepared by techniques known to those skilled in theart and comprise, for example, an immunologically effective amount ofany of the MtrE immunogens disclosed herein, optionally in combinationwith or fused to or conjugated to one or more other immunogens,including lipids, phospholipids, carbohydrates, lipopolysaccharides,inactivated or attenuated whole organisms and other proteins, of N.gonorrhoeae origin or other bacterial origin, a pharmaceuticallyacceptable carrier, optionally an appropriate adjuvant, and optionallyother materials traditionally found in vaccines.

In one embodiment, the invention provides a cocktail vaccine comprisingseveral immunogens, which has the advantage that immunity against one orseveral strains of a single pathogen or one or several pathogens can beobtained by a single administration. Examples of other immunogensinclude, but are not limited to, those used in the known DPT vaccines,HMW protein of C. trachomatis or fragments thereof, MOMP of C.trachomatis or fragments thereof, or PMPH or HtrA of C. trachomatis orfragments thereof (preferably epitope containing fragments), entireorganisms or subunits therefrom of Chlamydia, Neisseria, HIV,Haemophilus influenzae, Moraxella catarrhalis, Human papilloma virus,Herpes simplex virus, Haemophilus ducreyi, Treponema palladium, Candidaalbicans and Streptococcus pneumoniae, etc. The compositions mayoptionally comprise BIM protein or comprise an amino-terminal fragmentof HMW protein, i.e., a fragment comprising or consisting of residues1-100, 1-200, 1-300, 1-400, or 1-500 of the mature HMW protein.

In specific embodiments, the pharmaceutical or vaccine compositioncomprises an MtrE polypeptide and an HMW protein, or fragment thereof(for example at least 5, 8, 10, 20, 40, 50, 60, 80, 100, 150, 200, 300,400 or 500 amino acid fragment with an epitope containing fragmentthereof). In other specific embodiments, the composition comprises anMtrE polypeptide and a MOMP, or fragment thereof (for example an atleast 5, 8, 10, 20, 40, 50, 60, 80, 100, 150, 200, 300, 400 or 500 aminoacid fragment with an epitope containing fragment thereof).

The term “immunogenic amount” is used herein to mean an amountsufficient to induce an immune response to produce antibodies, T-cells,and/or cytokines and other cellular immune response components. In oneembodiment, the immunogenic composition is one that elicits an immuneresponse sufficient to prevent or reduce the likelihood of N.gonorrhoeae infections or to attenuate the severity of any preexistingor subsequent N. gonorrhoeae infection. An immunogenic amount of theimmunogen to be used in the vaccine is determined by means known in theart in view of the teachings herein. The exact concentration will dependupon the specific immunogen to be administered, but can be determined byusing standard techniques well known to those skilled in the art forassaying the development of an immune response.

The vaccine compositions of the invention elicit an immune response in asubject. Compositions which induce antibodies, including anti-MtrEprotein antibodies and antibodies that are opsonizing or bactericidalare one aspect of the invention. In one non-limiting embodiment of theinvention, an effective amount of a composition of the inventionproduces an elevation of antibody titer after administration. Inanother, more specific embodiment of the invention, approximately 0.01to 2000 μg, or 0.1 to 500 μg, or 50 to 250 μg of the MtrE proteinadministered is to a host. Compositions which induce T-cell responseswhich are bactericidal or reactive with host cells infected with N.gonorrhoeae are also an aspect of the invention. Additional compositionscomprise at least one adjuvant.

The combined immunogen and carrier or diluent may be an aqueoussolution, emulsion or suspension or may be a dried preparation.Appropriate carriers are known to those skilled in the art and includestabilizers, diluents, and buffers. Suitable stabilizers includecarbohydrates, such as sorbitol, lactose, mannitol, starch, sucrose,dextran, and glucose, and proteins, such as albumin or casein. Suitablediluents include saline, Hanks Balanced Salts, and Ringers solution.Suitable buffers include an alkali metal phosphate, an alkali metalcarbonate, or an alkaline earth metal carbonate. In select embodiments,the composition of the invention is formulated for administration tohumans.

The pharmaceutical and immunogenic compositions, including vaccines, ofthe invention are prepared by techniques known to those skilled in theart, given the teachings contained herein. Generally, an immunogen ismixed with the carrier to form a solution, suspension, or emulsion. Oneor more of the additives discussed herein may be added in the carrier ormay be added subsequently. The vaccine preparations may be desiccated orlyophilized, for example, by freeze drying or spray drying for storageor formulations purposes. They may be subsequently reconstituted intoliquid vaccines by the addition of an appropriate liquid carrier oradministered in dry formulation using methods known to those skilled inthe art, particularly in capsules or tablet forms.

An effective amount of the antigenic, immunogenic, pharmaceutical,including, but not limited to vaccine, composition of the inventionshould be administered, in which “effective amount” is defined as anamount that is sufficient to produce a desired prophylactic, therapeuticor ameliorative response in a subject, including but not limited to animmune response. The amount needed will vary depending upon theimmunogenicity of the MtrE protein or nucleic acid used, and the speciesand weight of the subject to be administered, but may be ascertainedusing standard techniques.

Immunogenic, antigenic, pharmaceutical and vaccine compositions mayfurther contain one or more auxiliary substance, such as wetting oremulsifying agents, pH buffering agents, or adjuvants to enhance theeffectiveness thereof. Immunogenic, antigenic, pharmaceutical andvaccine compositions may be administered to birds, humans or othermammals, including ruminants, rodents or primates, by a variety ofadministration routes, including parenterally, intradermally,intraperitoneally, subcutaneously or intramuscularly.

Alternatively, the immunogenic, antigenic, pharmaceutical and vaccinecompositions formed according to the present invention, may beformulated and delivered in a manner to evoke an immune response atmucosal surfaces. Thus, the immunogenic, antigenic, pharmaceutical andvaccine compositions may be administered to mucosal surfaces by, forexample, the nasal, oral (intragastric), ocular, bronchiolar,intravaginal or intrarectal routes. Alternatively, other modes ofadministration including suppositories and oral formulations may bedesirable. For suppositories, binders and carriers may include, forexample, polyalkalene glycols or triglycerides. Oral formulations mayinclude normally employed incipients such as, for example,pharmaceutical grades of saccharine, cellulose and magnesium carbonate.These compositions can take the form of microspheres, solutions,suspensions, tablets, pills, capsules, sustained release formulations orpowders and contain about 0.001 to 95% of the MtrE protein. Some dosageforms may contain 50 μg to 250 μg of the MtrE protein. The immunogenic,antigenic, pharmaceutical and vaccine compositions are administered in amanner compatible with the dosage formulation, and in such amount aswill be therapeutically effective, protective or immunogenic. Thecompositions may optionally comprise an adjuvant.

Further, the immunogenic, antigenic, pharmaceutical and vaccinecompositions may be used in combination with or conjugated to one ormore targeting molecules for delivery to specific cells of the immunesystem and/or mucosal surfaces. Some examples include but are notlimited to vitamin B12, bacterial toxins or fragments thereof,monoclonal antibodies and other specific targeting lipids, proteins,nucleic acids or carbohydrates.

Suitable regimes for initial administration and booster doses are alsovariable, but may include an initial administration followed bysubsequent administrations. The dose may also depend on the route(s) ofadministration and will vary according to the size of the host. Theconcentration of the MtrE protein in an antigenic, immunogenic orpharmaceutical composition according to the invention is in generalabout 0.001 to 95%, specifically about 0.01 to 5%.

The antigenic, immunogenic or pharmaceutical preparations, includingvaccines, may comprise as the immunostimulating material a nucleic acidvector comprising at least a portion of the nucleic acid moleculeencoding the MtrE protein.

A vaccine comprising nucleic acid molecules encoding one or more of theMtrE polypeptides of the present invention fusion proteins as describedherein, such that the polypeptide is generated in situ is provided. Insuch vaccines, the nucleic acid molecules may be present within any of avariety of delivery systems known to those skilled in the art, includingnucleic acid expression systems, bacterial and viral expression systems.Appropriate nucleic acid expression systems contain the necessarynucleotide sequences for expression in the patient such as suitablepromoter and terminating signals. The nucleic acid molecules may beintroduced using a viral expression system (e.g., vaccinia or other poxvirus, alphavirus retrovirus or adenovirus) which may involve the use ofnon-pathogenic (defective) virus. Techniques for incorporating nucleicacid molecules into such expression systems are well known to those ofordinary skill in the art. The nucleic acid molecules may also beadministered as “naked” plasmid vectors as described, for example, inUlmer et al. Science 259:1745-1749 (1992) and reviewed by Cohen, Science259:1691-1692 (1993). Techniques for incorporating DNA into such vectorsare well known to those of ordinary skill in the art. A vector mayadditionally transfer or incorporate a gene for a selectable marker (toaid in the identification or selection of transduced cells) and/or atargeting moiety, such as a gene that encodes a ligand for a receptor ona specific target cell, to render the vector target specific. Targetingmay also be accomplished using an antibody, by methods know to thoseskilled in the art.

Nucleic acid molecules (DNA or RNA) of the invention can be administeredas vaccines for therapeutic or prophylactic purpose. Typically a DNAmolecule is placed under the control of a promoter suitable forexpression in a mammalian cell. The promoter can function ubiquitouslyor tissue-specifically. Examples of non-tissue specific promotersinclude but are not limited to the early cytomegalovirus (CMV) promoter(described in U.S. Pat. No. 4,168,062) and Rous Sarcoma virus promoter(described in Norton and Coffin, Molec. Cell Biol. 5:281 (1985)). Thedesmin promoter (Li et al. Gene 78:243 (1989); Li & Paulin, J. Biol Chem266:6562 (1991); and Li & Paulin, J. Biol Chem 268:10401 (1993)) istissue specific and drives expression in muscle cells. More generally,useful vectors are described in, e.g., WO 94/21797 and Hartikka et al.,Human Gene Therapy 7:1205 (1996).

A composition of the invention can contain one or several nucleic acidmolecules of the invention. It can also contain at least one additionalnucleic acid molecule encoding another antigen or fragment derivative,including but not limited to, DPT vaccines, HMW protein of C.trachomatis or fragment thereof, MOMP of C. trachomatis or fragmentthereof, entire organisms or subunits therefrom of Chlamydia, Neisseria,HIV Haemophilus influenzae, Moraxella catarrhalis, Human papillomavirus, Herpes simplex virus, Haemophilus ducreyi, Treponema pallidium,Candida albicans and Streptococcus pneumoniae, etc. A nucleic acidmolecule encoding a cytokine, such as interleukin-1 or interleukin-12can also be added to the composition so that the immune response isenhanced. DNA molecules of the invention and/or additional DNA moleculesmay be on different plasmids or vectors in the same composition or canbe carried in the same plasmid or vector.

Other formulations of nucleic acid molecules for therapeutic andprophylactic purposes include sterile saline or sterile buffered salinecolloidal dispersion systems, such as macromolecule complexes,nanocapsules, silica microparticles, tungsten microparticles, goldmicroparticles, microspheres, beads and lipid based systems includingoil-in-water emulsions, micelles, mixed micelles and liposomes. Apreferred colloidal system for use as a delivery vehicle in vitro and invivo is a liposome (i.e., an artificial vesicle). The uptake of nakednucleic acid molecules may be increased by incorporating the nucleicacid molecules into and/or onto biodegradable beads, which areefficiently transported into the cells. The preparation and use of suchsystems is well known in the art.

A nucleic acid molecule can be associated with agents that assist incellular uptake. It can be formulated with a chemical agent thatmodifies the cellular permeability, such as bupivacaine (see, e.g., WO94/16737).

Cationic lipids are also known in the art and are commonly used for DNAdelivery. Such lipids include LIPOFECTIN™, also known as DOTMA(N-[1-(2,3-dioleyloxy)propyl]-N,N,N-trimethylammonium chloride), DOTAP(1,2-bis(oleyloxy)-3-(trimethylammonio)propane, DDAB(dimethyldioctadecylammonium bromide), DOGS (dioctadecylamidologlycyspermine) and cholesterol derivatives such as DC-Chol (3beta-(N—(N′,N′-dimethyl aminomethane)-carbamoyl) cholesterol. Adescription of these cationic lipids can be found in EP 187,702, WO90/11092, U.S. Pat. No. 5,283,185, WO 91/15501, WO 95/26356, and U.S.Pat. No. 5,527,928. Cationic lipids for DNA delivery can be used inassociation with a neutral lipid such as DOPE (dioleylphosphatidylethanolamine) as described in, e.g., WO 90/11092.

Other transfection facilitation compounds can be added to a formulationcontaining cationic liposomes. They include, e.g., spermine derivativesuseful for facilitating the transport of DNA through the nuclearmembrane (see, for example, WO 93/18759) and membrane-permeabilizingcompounds such as GAL4, Gramicidine S and cationic bile salts (see, forexample, WO 93/19768).

The amount of nucleic acid molecule to be used in a vaccine recipientdepends, e.g., on the strength of the promoter used in the DNAconstruct, the immunogenicity of the expressed gene product, the mode ofadministration and type of formulation. In general, a therapeutically orprophylactically effective dose from about 1 μg to about 1 mg,preferably from about 10 μg to about 800 μg and more preferably fromabout 25 μg to about 250 μg can be administered to human adults. Theadministration can be achieved in a single dose or repeated atintervals.

The route of administration can be any conventional route used in thevaccine field. As general guidance, a nucleic acid molecule of theinvention can be administered via a mucosal surface, e.g., an ocular,intranasal, pulmonary, oral, intestinal, rectal, vaginal, and urinarytract surface; or via a parenteral route, e.g., by an intravenous,subcutaneous, intraperitoneal, intradermal, intra-epidermal orintramuscular route. The choice of administration will depend on theformulation that is selected. For instance a nucleic acid moleculeformulated in association with bupivacaine is advantageouslyadministered into muscles.

Recombinant bacterial vaccines genetically engineered for recombinantexpression of nucleic acid molecules encoding an MtrE protein of thepresent invention include Shigella, Salmonella, Vibrio cholerae, andLactobacillus. Recombinant BCG and Streptococcus expressing MtrEpolypeptides can also be used for prevention or treatment of N.gonorrhoeae infections.

Non-toxicogenic Vibrio cholerae mutant strains that are useful as a liveoral vaccine are described in Mekalanos et al. Nature 306:551 (1983) andU.S. Pat. No. 4,882,278. An effective vaccine dose of a Vibrio choleraestrain capable of expressing a polypeptide or polypeptide derivativeencoded by a DNA molecule of the invention can be administered.

Attenuated Salmonella typhimurium strains, genetically engineered forrecombinant expression of heterologous antigens or not and their use asoral vaccines are described in Nakayama et al. Bio/Technology 6:693(1988) and WO 92/11361.

Other bacterial strains useful as vaccine vectors are described in Highet al., EMBO 11:1991 (1992); Sizemore et al., Science 270:299 (1995)(Shigella flexneri); Medaglini et al., Proc Natl. Acad. Sci. US 92:6868(1995) (Streptococcus gordonii); and Flynn, Cell Mol. Biol. 40:31(1994); WO 88/6626; WO 90/0594; WO 91/13157; WO 92/1796; and WO 02/21376(Bacille Calmette Guerin).

In genetically engineered recombinant bacterial vectors, nucleic acidmolecule(s) of the invention can be inserted into the bacterial genome,carried on a plasmid, or can remain in a free state.

When used as vaccine agents, recombinant bacterial or viral vaccines,nucleic acid molecules and polypeptides of the invention can be usedsequentially or concomitantly as part of a multistep immunizationprocess. For example, a mammal or bird can be initially primed with avaccine vector of the invention such as pox virus or adenovirus, e.g.,via the parenteral route or mucosally and then boosted several time witha polypeptide e.g., via the mucosal route. In another example, a mammalcan be vaccinated with polypeptide via the mucosal route and at the sametime or shortly thereafter, with a nucleic acid molecule viaintramuscular route.

An adjuvant can also be added to a composition containing an MtrEvaccine. To efficiently induce humoral immune responses (HIR) andcell-mediated immunity (CMI), immunogens are typically emulsified inadjuvants. Immunogenicity can be significantly improved if the immunogenis co-administered with an adjuvant. Adjuvants may act by retaining theimmunogen locally near the site of administration to produce a depoteffect facilitating a slow, sustained release of antigen to cells of theimmune system. Adjuvants can also attract cells of the immune system toan immunogen depot and stimulate such cells to elicit immune responses.

Many adjuvants are toxic, inducing granulomas, acute and chronicinflammations (Freund's complete adjuvant, FCA), cytolysis (saponins andPluronic polymers) and pyrogenicity, arthritis and anterior uveitis (LPSand MDP).

Immunostimulatory agents or adjuvants have been used for many years toimprove the host immune responses to, for example, vaccines. Intrinsicadjuvants, such as lipopolysaccharides, normally are the components ofthe killed or attenuated bacteria used as vaccines. Extrinsic adjuvantsare immunomodulators which are typically non-covalently linked toantigens and are formulated to enhance the host immune responses. Thus,adjuvants have been identified that enhance the immune response toantigens delivered parenterally. Aluminum hydroxide, aluminum oxide, andaluminum phosphate (collectively commonly referred to as alum) areroutinely used as adjuvants in human and veterinary vaccines. Theefficacy of alum in increasing antibody responses to diphtheria andtetanus toxoids is well established and a HBsAg vaccine has beenadjuvanted with alum.

Other extrinsic adjuvants may include chemokines, cytokines (e.g.,IL-2), saponins complexed to membrane protein antigens (immunestimulating complexes), pluronic polymers with mineral oil, killedmycobacteria in mineral oil, Freund's complete adjuvant, bacterialproducts, such as muramyl dipeptide (MDP) and lipopolysaccharide (LPS),as well as lipid A, and liposomes.

U.S. Pat. No. 6,019,982, incorporated herein by reference, describesmutated forms of heat labile toxin of enterotoxigenic E. coli (“mLT”).U.S. Pat. No. 5,057,540, incorporated herein by reference, describes theadjuvant, QS21, an HPLC purified non-toxic fraction of a saponin fromthe bark of the South American tree Quiliaja saponaria molina. 3D-MPL isdescribed in Great Britain Patent 2,220,211, which is incorporatedherein by reference.

U.S. Pat. No. 4,855,283 granted to Lockhoff et al. on Aug. 8, 1989,which is incorporated herein by reference, teaches glycolipid analoguesincluding N-glycosylamides, N-glycosylureas and N-glycosylcarbamates,each of which is substituted in the sugar residue by an amino acid, asimmunomodulators or adjuvants. Lockhoff reported thatN-glycosphospholipids and glycoglycerolipids are capable of elicitingstrong immune responses in both herpes simplex virus vaccine andpseudorabies virus vaccine. Some glycolipids have been synthesized fromlong chain-alkylamines and fatty acids that are linked directly with thesugars through the anomeric carbon atom, to mimic the functions of thenaturally occurring lipid residues.

U.S. Pat. No. 4,258,029 granted to Moloney, incorporated herein byreference, teaches that octadecyl tyrosine hydrochloride (OTH) functionsas an adjuvant when complexed with tetanus toxoid and formalininactivated type I, II and III poliomyelitis virus vaccine. Lipidationof synthetic peptides has also been used to increase theirimmunogenicity.

Therefore, according to the invention, the immunogenic, antigenic,pharmaceutical, including vaccine, compositions comprising an MtrEprotein, or an MtrE protein encoding nucleic acid or fragment thereof,vector or cell expressing the same, may further comprise an adjuvant,such as, but not limited to alum, mLT, LTR192G, QS21, R1131 DETOX™,MMPL, CpG DNA, MF59, calcium phosphate, PLG interleukin 12 (IL12), TLR7imidazoquinoline ligand 3M-019, resquimod (R848), small molecule mastcell activator MP7 and all those listed above. The adjuvant may beselected from one or more of the following: alum, QS21, CpG DNA, PLG,LT, 3D-mPL, or Bacille Calmette-Guerine (BCG) and mutated or modifiedforms of the above, particularly mLT and LTR192G. The compositions ofthe present invention may also further comprise a suitablepharmaceutical carrier, including but not limited to saline,bicarbonate, dextrose or other aqueous solution. Other suitablepharmaceutical carriers are described in Remington's PharmaceuticalSciences, Mack Publishing Company, a standard reference text in thisfield, which is incorporated herein by reference in its entirety.

Immunogenic, antigenic and pharmaceutical, including vaccine,compositions may be administered in a suitable, nontoxic pharmaceuticalcarrier, may be comprised in microcapsules, microbeads, and/or may becomprised in a sustained release implant.

Immunogenic, antigenic and pharmaceutical, including vaccine,compositions may desirably be administered at several intervals in orderto sustain antibody levels and/or T-cell levels. Immunogenic, antigenicand pharmaceutical, including vaccine, compositions may be used inconjunction with other bacteriocidal or bacteriostatic methods.

Also included in the invention is a method of producing an immuneresponse in an animal comprising immunizing the animal with an effectiveamount of one or more of the MtrE polypeptides or nucleic acid moleculesencoding the MtrE polypeptides of the invention, compositions comprisingthe same and vaccines comprising the same. The MtrE polypeptides,nucleic acids, compositions and vaccines comprising the MtrEpolypeptides of the invention may be administered simultaneously orsequentially. Examples of simultaneous administration include cases inwhich two or more polypeptides, nucleic acids, compositions, orvaccines, which may be the same or different, are administered in thesame or different formulation or are administered separately, e.g., in adifferent or the same formulation but within a short time (such asminutes or hours) of each other. Examples of sequential administrationinclude cases in which two or more polypeptides, nucleic acids,compositions or vaccines, which may be the same or different, are notadministered together or within a short time of each other, but may beadministered separately at intervals of, for example, days, weeks,months or years.

The polypeptides, nucleic acid molecules or recombinant bacterialvaccines of the present invention are also useful in the generation ofantibodies, as described herein, or T-cells. For T-cells, animals,including humans, are immunized as described above. Followingimmunization, PBL (peripheral blood lymphocytes), spleen cells or lymphnode cells are harvested and stimulated in vitro by placing largenumbers of lymphocytes in flasks with media containing human serum. Apolypeptide of the present invention is added to the flasks, and T-cellsare harvested and placed in new flasks with X-irradiated peripheralblood mononuclear cells. The polypeptide is added directly to theseflasks, and cells are grown in the presence of IL-2. As soon as thecells are shown to be N. gonorrhoeae specific T-cells, they are changedto a stimulation cycle with higher IL-2 concentrations (20 units) toexpand them.

Alternatively, one or more T-cells that proliferate in the presence of apolypeptide of the present invention can be expanded in number bycloning. Methods for cloning cells are well known in the art. Forexample, T-cell lines may be established in vitro and cloned by limitingdilution. Responder T-cells are purified from the peripheral bloodestablished in culture by stimulating with the nominal antigen in thepresence of irradiated autologous filler cells. In order to generateCD4⁺ T-cell lines, the MtrE polypeptides are used as the antigenicstimulus and autologous P3L or lymphoblastoid cell lines (LCL)immortalized by infection with Epstein Barr virus are used as antigenpresenting cells. To generate CD8⁺ T-cell lines, autologousantigen-presenting cells transfected with an expression vector whichproduces the relevant MtrE polypeptide may be used as stimulator cells.T-cell lines are established following antigen stimulation by platingstimulated T-cells in 96-well flat-bottom plates with PBL or LCL cellsand recombinant interleukin-2 (rIL2) (50 U/ml). Wells with establishedclonal growth are identified at approximately 2-3 weeks after initialplating and restimulated with appropriate antigen in the presence ofautologous antigen-presenting cells, then subsequently expanded by theaddition of low doses of IL2. T-cell clones are maintained in 24-wellplates by periodic restimulation with antigen and IL2 approximatelyevery two weeks.

T-cell preparations may be further enriched by isolating T-cellsspecific for antigen reactivity using the methods disclosed by Kendrickset al. in U.S. Pat. No. 5,595,881.

The vaccine compositions of the present inventions are useful inpreventing, treating or ameliorating disease symptoms in an animal, forexample a human, with a disease or disorder associated with N.gonorrhoeae infection or to prevent the occurrence or progression of adisease or disorder associated with N. gonorrhoeae infection in ananimal, for example a human.

The invention also provides for methods of inhibiting the growth of N.gonorrhoeae, with the methods comprising contacting the N. gonorrhoeaewith the antibody-containing pharmaceutical compositions describedherein.

The invention provides for methods of producing the isolated MtrEprotein described herein, with the methods comprising culturing a hostcell harboring a vector coding for the MtrE protein in cultureconditions in which expression of the MtrE protein from the vectoroccurs in the host, and purifying the MtrE protein from the cellculture.

In one embodiment, the methods comprise culture conditions in whichexpression of the MtrE expression from the vector comprise culturing thehost cell at a temperature below 37° C.

In another embodiment, the methods also comprise culture conditions inwhich expression of the MtrE expression from the vector compriseculturing the host cell for at least 8 hours.

In another embodiment, the methods also comprise culture conditions inwhich expression of the MtrE expression from the vector compriseculturing the host in a medium comprising an enzymatic digest of casein.

In another embodiment, the methods also comprise purifying the MtrEexpression from the cell culture comprises lysing the host cells in thepresence of at least two ionic detergents.

The invention also provides chimeric proteins comprising the MtrEpeptides described herein. In one embodiment, the MtrE peptidesdescribed herein fused to a porin protein or fragment thereof. Inparticular, Porin B (PorB) sequences can be fused to the MtrE peptidesdescribed herein. N. gonorrhoeae strains are classified based on theirPorB serotype, PorB1A and PorB1B, and within each serotype there areseveral antigenic variants due to differences in the amino acidsequences of surface-exposed regions. The PorB sequences that can beincorporated into or fused to the MtrE peptides include but are notlimited to one or more surface-exposed loops of commonly expressedPorB1A or PorB1B molecules. Examples of the surface exposed loops thatcan be incorporated into or fused to the MtrE peptides of the presentinvention include but are not limited to those listed in Table VI below.

TABLE VI Examples of PorB1A or PorB1B peptidesgenetically engineered into MtrE peptides Peptide Sequence PIA1TIKAGVETSRSVAHHGAQADRVKTA TEIADLG (SEQ ID NO: 5) PIA2AIWQLEQKAYVSGTDTGWGNRQSFI GLKG (SEQ ID NO: 6) PIA3VLKDTGGFNPWEGKSYYLGLSNIAQ PEERHVSV (SEQ ID NO: 7) PIA5VQYAGFYKRHSYTTEKHQVHRLVGG YDH (SEQ ID NO: 8) PIA6SVAVQQQDAKLTWRNDNSHNSQTEV AATAA (SEQ ID NO: 9) PIA7VSYAHGFKGSVYDADNDNTYDQVVV GAEYDF (SEQ ID NO: 10) PIA8ALVSAGWLQRGKGTEKFVATVGGVG LRH (SEQ ID NO: 11) PIA8-aGKGTEK (SEQ ID NO: 12) PIB2 KAVWQLEQGASVAGTNTGWGNKQSFIGLKGGF (SEQ ID NO: 13) PIB4 AGFSGSVQYAPKDNSGSNGESYHVGLN (SEQ ID NO: 14) PIB5 GLFQRYGEGTKKIEYDGQTYSIPSLFVEKLQVHR (SEQ ID NO: 15) PIB6 AAQQQDAKLYGAMSGNSHNSQTEVAAT (SEQ ID NO: 16) PIB7 HGFKGTVDSANHDNTYDQVVVGAEY (SEQ ID NO: 17)

In one specific embodiment, the chimeric proteins of the presentinvention comprise the sequence of MtrE with the PIA8-a sequence (loop 8surface exposed residues on PorB1A) being fused into surface exposedLoop 1 of MtrE.

(SEQ ID NO: 4) MNTTLKTTLT SVAAAFALSA CTMIPQYEQP KVEVAETFQNDTSVSSIRAV DLGWHDYFAD PRLQKLIDIA LERNTSLRTAVLNSEIYRKQ YMIERNNLLP TLAANANGSR QGSLSGGKGTEKGNVSSSYN VGLGAASYEL DLFGRVRSSS EAALQGYFASVANRDAAHLS LIATVAKAYF NERYAEEAMS LAQRVLKTREETYNAVRIAV QGRRDFRRRP APAEALIESA KADYAHAARSREQARNALAT LINRPIPEDL PAGLPLDKQF FVEKLPAGLSSEVLLDRPDI RAAEHALKQA NANIGAARAA FFPSIRLTGSVGTGSVELGG LFKSGTGVWA FAPSITLPIF TWGTNKANLDVAKLRQQAQI VAYESAVQSA FQDVANALAA REQLDKAYDALSKQSRASKE ALRLVGLRYK HGVSGALDLL DAERSSYSAEGAALSAQLTR AENLADLYKA LGGGLKRDTQ TGK

In specific embodiments, the invention provides isolated proteinfragments with amino acid sequences comprising or alternativelyconsisting of amino acid residues 23-473 of SEQ ID NO: 4, amino acidresidues 23-161 of SEQ ID NO: 4 or an amino acid residues 319-473 of SEQID NO: 4. In other specific embodiments, the invention provides isolatedMtrE peptides with amino acid sequences comprising or alternativelyconsisting of amino acid residues 112-124 of SEQ ID NO: 4.

In specific examples, the invention is directed to isolated variants ofMtrE proteins comprising, or in the alternative consisting of an aminoacid sequence that is at least 80% identical to residues 23-473 of SEQID NO: 4, or an amino acid sequence that is at least 80% identical toresidues 23-161 of SEQ ID NO: 4. In additional embodiments, theinvention is directed to isolated MtrE proteins that have amino acidsequences comprising, or in the alternative consisting of sequences,that are at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%,96%, 97%, 98%, 99% and 100% identical to residues 23-473 of SEQ ID NO:4. In more embodiments, the invention is directed to isolated MtrEproteins that have amino acid sequences comprising, or in thealternative consisting of sequences, that are at least 85%, 86%, 87%,88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100%identical to residues 23-161 of SEQ ID NO: 4. In still more embodiments,the invention is directed to isolated MtrE proteins that have amino acidsequences comprising, or in the alternative consisting of sequences,that are at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%,96%, 97%, 98%, 99% and 100% identical to residues 112-124 of SEQ ID NO:4.

EXAMPLES Example 1—Construction of MtrE Expression Plasmids

The mtrE expression plasmid, pETAD-1, was constructed by PCRamplification of a previously described mtrE plasmid, pCR-mtrE (Warneret al., 2007). The forward primer, oAJD-36(GGCAATGTCATGATCCTCAATACGAGCAGC (SEQ ID NO: 18)) contains a BspHl site(indicated in boldface type) and amplifies mtrE from residue 3(methionine) of the mature protein. The reverse primer, oAJD-18(ATAGTTTAGCGGCCGCTTTGCCGGTTTGGGTATCCC (SEQ ID NO: 19)) contains a NotIsite (indicated in boldface type), and amplifies mtrE from the finalresidue (residue 447-lysine). PCR was performed with Taq polymerase(Qiagen) and the resulting PCR product was ligated into pET28 b+(EMDBiosciences) to create expression plasmid pETAD-1. pETAD-1 encodes arecombinant MtrE protein under the control of a T7 promoter that lacksthe amino terminal signal sequence and has 5 additional residues encodedby pET28 b+ immediately prior to the C-terminal six-histidine tag toprovide restriction site compatibility (C-terminal sequence: AAALEHHHHHH(SEQ ID NO: 20)).

The pETAD-2 (truncated N-terminal recombinant MtrE) and pETAD-3(truncated C-terminal recombinant MtrE) expression vectors wereconstructed in the manner described above. To create pETAD-2, PCRamplification was performed with the forward primer oAJD-36 (describedabove) and the reverse primer oAJD-37(ATAGTTTAGCGGCCGCAACGCTGGCAAAATAGCC (SEQ ID NO: 21)) which contains aNotI site (indicated in boldface type). The resulting construct encodesa recombinant, truncated MtrE (residues 3-135) fused to the C-terminalsequence AAALEHHHHHH, incorporating a six-histidine tag. pETAD-3 wascreated by PCR amplification with the forward primer oAJD-38(CATGCCATGGGCAGCGTCGGTACGGG (SEQ ID NO: 22)) which contains a NcoI site(indicated in boldface type) and reverse primer oAJD-18 (describedabove). The resulting construct encodes a recombinant, truncated MtrE(residues 293-447) fused to the C-terminal sequence AAALEHHHHHH (SEQ IDNO: 20), incorporating a six-histidine tag.

All other vectors encoding various lengths of recombinant MtrE areconstructed in a manner similar to that described above, utilizing PCRamplification and commercially-available vectors. The expression hostsfor the pETAD vectors were commercially available E. coli strainsincluding, but not limited to BL21 (DE3) (EMD Millipore).

Example 2—Construction of MtrE-PorB Expression Plasmids

MtrE-PorB fusion proteins will be created using a Gene SOEing (Horton etal., 1990) technique where the porin loop sequence is encoded by theprimers. The mtrE coding sequence will be amplified from the pCR-mtrEplasmid (Warner et al., 2007) using a two-step PCR method with theoutside primers oAJD-36 and oAJD-18. The PorB loop sequence will beincorporated at either of putative loop regions of MtrE in a manner thatdoes not compromise the integrity of this surface-exposed domain. Inselect constructs, the PorB loop sequences are added to the N-terminusof recombinant MtrE proteins. In select constructs, the PorB loopsequences are added to the C-terminus of recombinant MtrE proteins. Inadditional select constructs, the PorB loop sequences are added internalto the recombinant MtrE proteins.

Examples of PorB loop sequences that will be incorporated into the MtrEproteins are shown in Table VI above.

Example 3—Recombinant Protein Expression and Purification

Recombinant MtrE proteins were expressed using baffled flasks containing400 ml of NZCYM broth (pH 7.0) with 30 μg/ml kanamycin. Once culturesreached a 600 nm optical density of 0.6 to 0.9, IPTG(isopropyl-β-d-thiogalactopyranoside) was added to 0.5 mM. Expressionproceeded overnight (^(˜)18 hrs) at 25° C. Following expression,bacteria were pelleted by centrifugation at 10,000×g for 10 minutes at4° C. Cell pellets were then stored overnight at −80° C.

MtrE was purified by thawing the pellets on ice and suspension of thebacterial cell pellet in BugBuster (EMD Millipore), 5 ml/gram pelletweight. Lysozyme (Sigma) 0.5 mg/ml, benzonase (EMD Millipore) 1 μl/ml,and protease inhibitors (EMD Millipore) were added and the suspensionwas incubated at room temperature for 20-30 minutes on a rockingplatform. Insoluble debris/proteins were removed by centrifugation at16,000×g for 20 minutes at 4° C. The supernatant was removed forpurification of soluble MtrE while the pellet was stored at −80° C. forpurification of insoluble MtrE.

Soluble MtrE was purified by adding the supernatant to a Ni-NTA resin(EMD Millipore), equilibrated with binding buffer (300 mM NaCl, 50 mMNaH₂PO₄, 10 mM imidizole; pH 8.0), incubated 60 minutes, rocking at 4°C. The bound protein was washed twice with 20 bed volumes of wash buffer(300 mM NaCl, 50 mM NaH₂PO₄, 20 mM imidizole; pH 8.0) and eluted (300 mMNaCl, 50 mM NaH₂PO₄, 200 mM imidizole; pH 8.0). All buffers contained0.7% n-Dodecyl-β-D-Maltopyranoside (Affymetrix). Following purificationthe protein was run through a buffer exchange desalting column (Pierce)and stored in PBS+0.7% n-Dodecyl-β-D-Maltopyranoside at −20° C. Proteinconcentration was determined by Nanodrop using the extinctioncoefficient of the protein.

MtrE was purified from inclusion bodies (insoluble MtrE) by thawing theinsoluble debris/protein pellet described above on ice. The pellet wassuspended in BugBuster (EMD Millipore), 5 ml/gram of pellet. Lysozyme(0.5 mg/ml) and protease inhibitors (EMD Millipore) were added and thesuspension was incubated at room temperature for 5 minutes. Followingincubation 6 volumes of 1:10 diluted BugBuster were added and thesolution was subjected to centrifugation at 16,000×g for 15 minutes, 4°C. The supernatant was removed, and the resuspension and centrifugationwere repeated two additional times. The resulting inclusion bodies weresuspended in 6M Gu-HCL to denature the protein. MtrE was re-naturedusing a single-step dialysis method. The denatured protein was diluted1:2 in 6M Gu-HCL, added to a Slide-A-Lyzer (20 k molecular weight cutoff) dialysis cassette (Pierce) and dialyzed against 100-fold excessbinding buffer+0.7% n-Dodecyl-β-D-Maltopyranoside at 4° C. overnight.The buffer was exchanged once and precipitate was removed bycentrifugation at 12,000×g for 10 minutes, 4° C. Following overnightdialysis precipitate was once again removed by centrifugation and theprotein was bound to Ni-NTA resin (EMD Millipore) using the protocol andbuffers described above for purification of soluble MtrE.

Example 4—Immunization

Female BALB/c mice (National Cancer Institute, Bethesda, Md.) wereimmunized either subcutaneously (SQ) (systemic immunization) orintranasally (IN) (mucosal immunization) with MtrE purified from eitherthe soluble or insoluble fractions at a dose of 10-30 μg/mouse. Thefollowing adjuvants were used: TiterMax Gold (CytRx) (SQ only), awater-in-oil adjuvant (dose: ≥50% of total immunization volume);Monophosphoryl A (MplA), a TLR4 agonist approved for human use (dose: 25μg/mouse); Cholera Toxin (CT), a potent mucosal adjuvant (dose: 1μg/mouse). Of course, other adjuvants can also be used, including butnot limited to, IL-12, CpG (ODN 1826), imidazoquinoline compound 3M-019,MP7, resiquimod (R848).

Example 5—Production of Antisera Against Predicted Surface-Exposed MtrELoops

The surface-exposed MtrE loop sequences were predicted as follows. Theouter membrane proteins ToIC (E. coli) and OprM (Pseudomonasaeruginosa), which are functionally similar to MtrE, are predicted toform two surface-exposed loops. The MtrE predicted amino acid sequenceis most closely related to P. aeruginosa, thus regions in the predictedamino acid sequence of MtrE with homology to the four transmembraneregions that flank the two surface exposed loops in OprM were sought.Four regions were found in MtrE with homology to the OprM™ sequences S1,S2, S3 and S4, and the intervening sequences in the MtrE protein[GSLSGGN (SEQ ID NO: 2) (predicted surface loop 1, amino acids 112-118)and GSVGTGSVELGGLFKSGTGV (SEQ ID NO: 3) (predicted surface loop 2; aminoacids 313-332)] were identified as potentially being surface-exposed.These predictions were supported by in silico analysis of the predictedstructure. Affinity-purified rabbit antibodies against linear peptidesthat correspond to these regions were produced commercially (Bethyllaboratories) and tested by Western blot to confirm the specificity ofthe antisera.

Example 6—Bactericidal Assay

Bactericidal assays were performed as described previously (Cole andJerse, 2009) with serum obtained by retroorbital bleed from miceimmunized with MtrE. Normal human serum (NHS) was used as the complementsource at the following concentrations: gonococcal strain FA1090, 4%;strain FA19, 10%; strain MS11, 1%; strain RD-1 (MtrE⁻), 10%. HeatInactivated NHS was used as a control. Assays were performed intriplicate and the dilution of anti-MtrE serum resulting in 50% killingof the bacteria was reported.

Example 7—Surface Binding

To examine whether MtrE-specific mouse antibodies recognize thegonococcal surface, a flow cytometry assay was used. Briefly, wild typeand MtrE-deficient N. gonorrhoeae strains were grown to mid-log phaseand filtered through a 1.2 μm filter. Bacteria were added to a 96-wellplate and subjected to centrifugation at 1500 RPM. The bacteria weresuspended in serum (1:50-1:100 dilution) for 1 hour at room temperature.Bacteria were washed in 1% BSA (Ig-free, Sigma) and suspended in Alexa488-conjugated anti-mouse secondary (1:250, Molecular Probes) for 30minutes. Bacteria were then washed as described above and re-suspendedin 100 μl HBSS2+ before addition of 4% paraformaldehyde. Normal mouseserum was used as a control for surface binding. Samples were analyzedusing a BD LSRII cytometer.

Example 8—Inhibition of Efflux Pump Function

To test whether MtrE-specific antisera could increase the susceptibilityof N. gonorrhoeae to the bactericidal activity of human cathelicidinLL37 (hLL37) by blocking MtrCDE efflux pump function, bacteria weresuspended in minimal essential medium (MEM) and added to eppendorf tubesthat contained MEM alone or MEM containing decreasing concentrations ofantisera against the loop 1- or loop 2-peptides (2.5×10⁵ CFU per tube).Antiserum to a peptide that corresponds to the semivariable (SV) loop ofthe gonococcal Opa proteins (Opa_(SV)) (Cole and Jerse, 2009) was usedas a negative control. Following 20 min incubation at 37° C., thebacterial suspensions were pipetted into a microtiter plate containingincreasing concentrations of hLL37 (0 to 12.5 ug/ml); finalconcentration of bacteria per well: 3×10⁴ CFU. The microtiter plateswere incubated for 1 hr at 37° C. after which a constant volume of GCBwas added and 25 μl of the final suspensions were inoculated onto GCagar. The number of CFU recovered from each concentration of hLL37following overnight incubation was determined.

Example 9—Construction of MtrE-Porin Expression Plasmids

A MtrE-Porin fusion protein where Loop 8A from PorB was fused to Loop1of MtrE was created as described in the construction of MtrE-PorBexpression plasmids methods. The porin P1A8a sequence was incorporatedat residue 96, fusing the porin epitope to the first putativesurface-exposed domain of MtrE. Recombinant protein was expressed andpurified as described in Example 3 above.

1-20. (canceled)
 21. A vector comprising a polynucleotide encoding anMtrE protein or fragment thereof.
 22. The vector of claim 21, whereinthe MtrE protein is SEQ ID NO: 1
 23. The vector of claim 21 wherein thepolynucleotide encodes an amino acid sequence of residues 23-467 of SEQID NO:
 1. 24. The vector of claim 21 wherein the polynucleotide encodesan amino acid sequence of residues 23-155 of SEQ ID NO:
 1. 25. Thevector of claim 21 wherein the polynucleotide encodes an amino acidsequence of residues 313-467 of SEQ ID NO:
 1. 26. A host cell comprisingthe vector of claim
 21. 27. The host cell of claim 23 wherein the hostcell is an E. coli cell.